1. Field of the Invention
The present invention relates to a method and a device for transmitting information from a switching system to a subscriber terminal and more particularly to such method and device that inform the subscriber of the name of a communication service related to him and the activation/deactivation of the communication service.
2. Description of the Related Art
At present, the development of communication technology allows for providing a variety of communication services to the subscribers via a telephone network. Therefore, more and more people subscribe to plural communication services. In case a subscriber is a member of plural communication services, the name of the communication service to which the subscriber has subscribed and activation/deactivation of the communication service required to be reported to the subscriber.
There are various signal transmission methods regarding communication services. For example, we can refer to the method for transmitting a voice signal indicative of the name of a communication service to a subscriber, a method for transmitting a different tone for each communication service and a method for transmitting tones respectively indicating the activation and deactivation of a communication service.
In the above-mentioned methods, aural signals or tones to identify each communication service, and aural signals or tones to differentiate activation or deactivation of each communication service are identified for a switching system or equipment connected to a switching system. When subscriber hooks up, the switching system recognizes the off-hook signal and reads aural signals or tones to differentiate the name of the communication service to which the subscriber has subscribed and activation/deactivation of the communication service. Further, the switching system sends the read aural signals or tones to the subscriber terminal.
For example, in the case of a subscriber of an analog network or ISDN, while any service is activated, the switching system sends a dial tones to identify the communication service when the subscriber hooks up. The subscriber can recognize the activated communication service by the dial tones sent by the switching system.
Some ISDN terminals are provided with a service status pilot lamp (Feature lamp). The subscriber registers service identification data to identify a communication service to an ISDN terminal. When the communication service is activated, the switching system sends the communication service identification information to identify the communication service to the ISDN terminal. When the ISDN terminal receives the communication service identification information from the switching system, the service status pilot lamp is lighted. When the communication service is deactivated the switching system sends a signal showing deactivation of a communication service to the ISDN terminal. When the ISDN terminal receives the signal from the switching system, the service status pilot lamp is put out. In detail, when a communication service is activated, the switching system identifies the ISDN terminal which is a member of the communication service. Then, the switching system sends the communication service identification information of the communication service to the ISDN terminal.
The subscriber can recognize the type of a service and activation/deactivation of the service by reference to the service status pilot lamp of the ISDN terminal. If the ISDN terminal is powered off due to any cause, the subscriber executes a "service status interrogation procedure" (Interrogation). That is, when the subscriber sends a specific signal to the provider of the communication service, it detects the status of activation of the communication service. When the provider detects the communication service is activated, it sends the communication service identification information of the communication service to the subscriber. The above-mentioned transmission of the communication service identification information allows the service status pilot lamp corresponding to activation of a communication service of the subscriber's ISDN terminal to be lit.
If a call to a subscriber of an automatic answering telephone service cannot be accepted due to a busy call or absence, the switching system transfers the call to a message storage device. When the subscriber finishes the call or hooks up the terminal after he returns, the switching system sends a dial tone showing the activation of the automatic answering telephone service to the subscriber. The subscriber can recognize the activation of the automatic answering telephone service by the dial tone and receive the calling subscriber's message from the message storage device.
In case of an ISDN terminal, the subscriber is informed of storage of a message by lighting of the service status pilot lamp corresponding to the automatic answering telephone service. However, in the case of an analog terminal, if a subscriber is a member of plural communication services, he must differentiate plural tones because the type of a communication service and activation/deactivation of the communication service are informed by dial tones. If a subscriber is a member of further more communication services, he cannot differentiate the dial tones and may not be able to know what communication service is activated.
On the other hand, in the case of ISDN, even if a terminal is provided with a service status pilot lamp (Feature lamp), the subscriber must set up the lamp for corresponding to each service and the procedure is intricate. Further, another problem that a "service status interrogation procedure (Interrogation)" must be executed for each service which leads to the intricate operation.
The automatic answering telephone service still informs the subscribers that a call to the subscriber is transferred and stored as a message by a special dial tone. The method of differentiating services by a dial tone imposes a burden on subscribers and may make a service less significant.